Plasma enhanced pulsed layer deposition

ABSTRACT

A process system and a deposition method for depositing a highly controlled layered film on a workpiece is disclosed. The basic component of the present invention apparatus is a pulsing plasma source capable of either exciting or not-exciting a first precursor. The pulsing plasma source includes an energy source to generate a plasma, and a plasma adjusting system to cause the plasma to either excite or not-excite a precursor. The precursor could flow continuously (an aspect totally new to ALD), or intermittently (or pulsing, standard ALD operation process). The present invention further provides a method to deposit highly controlled layered film on a workpiece. The method comprises the steps of pulsing the plasma to excite/not-excite the precursors and the ambient to deposit and modify the depositing layers. This procedure then can be repeated alternately until the film reaches a desired thickness.

FIELD OF THE INVENTION

[0001] The present invention relates generally to apparatus forprocessing of semiconductor wafers, and more particularly to a systemand method for deposition of thin films.

[0002] BACKGROUND OF THE INVENTION

[0003] A fundamental process in IC fabrication is chemical vapordeposition (CVD), which uses vapor precursors to deposit thin films on asemiconductor substrate. The reactor used for CVD processes includes aprecursor delivery system, a substrate and an energy source to decomposethe precursor vapor to reactive species to allow a thin film to form onthe substrate (CVD process). Effective power sources are heat and plasmaenergy such as radio frequency (RF) power, microwave energy (MW), lowfrequency (10 KHz -1 MHz) power, and optical energy (e.g. a laser orultraviolet light) which decompose the introduced precursors. Plasmaenergy power is below 6000W. The amount of power required in eachprocess is determined by the process reaction and a typical power levelis between 500-1000W. Also, the substrate could be biased or heated (to100° C. -1200° C.) to promote the reaction of the decomposed atoms ormolecules and to control the physical properties of the formed films.

[0004] Traditionally, precursors used in semiconductor CVD processes aregaseous. An example of a CVD process to deposit silicon dioxide (SiO₂)is to use gaseous precursors such as silane gas (SiH₄) and oxygen gas(O₂):

SiH₄(gas)+O₂(gas)−(heat)→SiO₂(solid)+2H₂(gas)

[0005] The basic requirements of a precursor are that the desiredproduct (in this example, SiO₂) is solid, and all other products aregases (in this example, H₂) to be exhausted away. The energy requiredfor the reaction to take place is the thermal energy, about 400-800° C.

[0006] To broaden the processes, more and more liquid and solidprecursors have been used, especially in the area of metal-organicchemical vapor deposition (MOCVD). To perform this task, a liquidprecursor is typically turned into vapor, and the vapor is thendecomposed and reacts on the substrate. A solid precursor must often bedissolved into a solvent to form a liquid precursor. The liquidprecursor then needs to be converted into vapor phase before beingintroduced into the deposition zone. An example of CVD process todeposit copper (Cu) is to use liquid precursor vapor copperHexaFluoroACetylacetone TriMethylVinylSilane (hfac-copper-tmvs,C₅HO₂F₆—Cu—C₅H₁₂Si):

2Cu-hfac-tmvs (vapor)−(heat)→Cu (solid)+hfac-Cu-hfac (gas)+2tmvs (gas)

[0007] Another deposition technique is the atomic layer epitaxy (ALE)process. In ALE, the precursors are pulsed sequentially into the ALEprocess chamber with each precursor taking turn to generate a chemicalsurface reaction at the substrate surface to grow about one atomic layerof the material on the surface. The growth of one atomic layer in ALE iscontrolled by a saturating surface reaction between the substrate andeach of the precursors. Sometimes a reduction sequence activated withextra energy such as heat or photon can be used to re-establish thesurface for a new atomic layer. The fundamental of ALE is having aminimum of two different chemical reactions at the surface with eachreaction carefully controlled to generate only one atomic layer. Anexample of ALE is the growth of ZnS at ˜470° C. using sequential flow ofelemental zinc and sulfur as precursors as disclosed by Suntola et al.,U.S. Pat. No. 4,058,430. Another example of ALE is the growth ofgermanium (Ge) on silicon substrate at˜260-270° C. using a first steppulsing of GeH₄ vapor flow to generate an atomic layer coverage of GeH₄and a second step pulsing of an Xe lamp exposure to decompose thesurface GeH₄ as disclosed by Sakuraba et al, J. Cryst. Growth, 115(1-4)(1991) page 79.

[0008] ALE process is a special case of atomic layer deposition (ALD)process. The focus of ALE is the deposition of epitaxial layers, meaningperfect crystal structure. In contrast, ALD process seeks to deposit onelayer at a time with the focus on film uniformity, not single crystalstructure.

[0009] The major drawbacks of CVD and ALD processes are the hightemperature needed for the chemical reactions and the limited number ofavailable precursors. Each CVD or ALD process always starts with anextensive evaluation of various precursors and their chemical reactionsto see if there is any suitable process reaction.

[0010] To lower the temperature needed for the chemical reaction, and tofurther promote possible reaction, plasma energy is being used to excitethe precursors before the reaction takes place in CVD processes. Suchprocesses are called plasma enhanced CVD (PECVD) processes. An energysource using radio frequency (RF) power or microwave (MV) power can beused to generate a plasma, which is a mixture of excited gaseousspecies, to supply energy to the precursors thus promoting the chemicalreactions.

[0011] However, there is no plasma enhanced ALD process or equipment.The main advantages of a plasma enhanced ALD are the low temperatureneeded for the reaction to occur, and the addition of plasma energy toexcite the precursors, leading to more selections of precursors.Furthermore, a plasma treatment could modify the surface condition,leading also to a wider range of precursor selection.

[0012] It would be advantageous if there is a plasma enhanced ALDsystem.

[0013] It would be advantageous if a plasma treatment could beincorporated in an ALD process.

SUMMARY OF THE INVENTION

[0014] Accordingly, a plasma enhanced atomic layer deposition (PEALD)apparatus is provided to offer atomic layer deposition capability usingplasma source to excite the precursor. In addition to the prior artsurface reactions using non plasma-excited precursor, the presentinvention also offer surface reactions using plasma-excited precursor.With plasma-excited precursor, the surface reaction could be eitherdeposition reaction, or material modification by plasma bombardment.

[0015] The basic component of the present invention apparatus is apulsing plasma source capable of either exciting or not-exciting a firstprecursor. The pulsing plasma source includes an energy source togenerate a plasma, and a plasma adjusting system to cause the plasma toeither excite or not-excite a precursor. The precursor could flowcontinuously (an aspect totally new to ALD), or intermittently (orpulsing, standard ALD operation process).

[0016] The plasma power source is preferably an inductive coupled plasma(ICP) source, but any plasma source such as capacitance plasma source,microwave guide plasma source, electron cyclotron resonance plasmasource, magnetron plasma source, DC power plasma source, etc. worksequally well.

[0017] In the simplest design, the plasma adjusting system is a powerswitch, causing the plasma to either ON or OFF. When the plasma is OFF,the precursor is not excited by the plasma (because there is no plasma).When the plasma is ON, the precursor is excited by the plasma. Typicalplasma power when ON is between 15 to 6000W. The low power is used forsensitive precursors such as those containing organic components. Thetiming for this design is long, in the order of many seconds because ofthe needed time for the plasma to stabilize.

[0018] To shorten the plasma stabilizing time, the plasma adjustingsystem comprises a two-level plasma power switch: a low power firstlevel and a high power second level. The first level plasma powergenerates a plasma, but not enough to excite the precursor, either bylow enough power or the precursor is far away from the plasma. Thesecond level plasma power generates a large enough plasma to excite theprecursor. By using a first level plasma, the stabilizing time is muchshorter because the plasma is already present, and powering up from thefirst level to the second level power takes shorter time. The firstpower level is typically from 15 to 300W and the second power level,from 100 to 6000W.

[0019] Another way to block the plasma is to apply an electric field.The plasma adjusting system then comprises an electrode having apotential. By varying the potential, the plasma could either passthrough or be confined. At ground potential, the electrode willterminate the plasma, allowing no plasma to pass through. At a positivepotential, the electrode will repel all positive charges in the plasmafield, allowing only negative charges such as electrons, to passthrough. At floating potential, meaning the electrode is not connected,the electrode will obtained a self-potential, but the plasma will passthrough. The electrode could be the workpiece support, or a wire meshabove the workpiece.

[0020] The present invention apparatus further comprises a heater sourceto bring the workpiece to a process temperature.

[0021] The present invention apparatus further comprises a secondprecursor positioned in a way as always not being excited by the plasma,and a third precursor positioned in a way as always being excited by theplasma. These precursors complement the pulsing action of the plasmasource on the first precursor for a wider selection of processconditions.

[0022] The present invention apparatus further comprises pulsing systemsfor the first, second and third precursors. The pulsing systems furtherallow the sequential deposition of these precursors. Together with thepulsed plasma, the pulsed precursors offers more control to the timingof the process. The first, second and third precursors could comprise aplurality of precursors with different pulsing systems. As such, theprecursors could pulsed together at the same time, pulsed at differenttimes, or pulsed in a synchronized fashion such that when one of thepulsed precursors is on, the others are off.

[0023] The present invention further provides a method to deposit atomiclayer using plasma enhanced ALD system. The method comprises the stepsof

[0024] a) the plasma does not excite the first precursor flow

[0025] b) the plasma does excite the first precursor flow

[0026] with the stepping sequence interchangeable, meaning either a)before b) or b) before a). This procedure can then be repeatedalternately until the film reaches a desired thickness.

[0027] Generally, step a) deposits a layer of material from theun-excited precursor to the workpiece surface. Step b) could deposit adifferent layer from the excited precursor to the workpiece surface, orstep b) could modify the previously deposited layer with the excitedprecursor. Therefore, with step b) depositing, the method grows a thinfilm on a substrate by

[0028] a) subjecting the substrate to the vapor of the un-excitedprecursor to form a layer of material on the substrate;

[0029] b) subjecting the thus-formed surface to the vapor of the excitedprecursor to form a different layer of material on the thus-formedsurface.

[0030] With the step b) modifying, the method grows a thin film by

[0031] a) subjecting the substrate to the vapor of the un-excitedprecursor to form a layer of material on the substrate;

[0032] b) subjecting the thus-formed surface to the vapor of the excitedprecursor to modify the material of the deposited layer on thethus-formed surface.

[0033] The present invention method also provides for the presence of asecond precursor always not-excited and a third precursor alwaysexcited. Steps a) and b) then have the second and third precursorstogether with the first precursor. The addition of the second and thethird precursors offer the broadening of the process parameters, thusallow the development of many advanced processes.

[0034] The precursor flows in steps a) and b) above can be continuous orintermittent (pulsing). An example of continuous precursor flow isTetraDiMethylAminoTitanium (TDMAT) in a process used to produce TiNfilm. With low enough substrate temperature, TDMAT precursor does notreact at the substrate. With plasma on, TDMAT is decomposed and forms athin TiN layer. With pulsing plasma, a highly controlled layered TiNfilm is formed. Adding a continuous flow of non-excited secondprecursor, nitrogen gas for example, could reduce the TDMAT partialpressure for controlling the deposition rate. Adding a continuous flowof third plasma-excited precursor, nitrogen and hydrogen for example,could change the film composition such as reducing the amount of carbon.

[0035] The first, second and third precursors each could comprise aplurality of precursors. With pulsing precursors, meaning a precursorflow is either on or off, a plurality of precursors offer sequentialflow. For example, the first of the first precursors could flow, andthen stop, then the second of the first precursors could flow, and thenstop, and so on, until the last of the first precursors, and then returnto the first of the first precursors.

[0036] Also, with pulsing precursors, the present invention methodincludes 2 more steps:

[0037] c) when the precursor flow is off, the plasma does not excite theprocess chamber ambient residue enough to have an effect on theworkpiece;

[0038] d) when the precursor flow is off, the plasma does excite theprocess chamber ambient residue enough to have an effect on theworkpiece.

[0039] with the stepping sequence interchangeable, meaning either c)before d) or d) before c). The stepping sequence between a), b), c) andd) is also interchangeable depending on the process development. Thedifference between steps C, d and steps a, b is the absence of theprecursor flow. Steps a, b occur when there is a precursor flow andsteps c, d occur when there is no precursor flow. Without precursorflow, the ambient still has enough residue gaseous particles to sustaina plasma. This plasma, though without active precursor, still has enoughenergy to have an effect on the deposited film. With 4 steps, there are4×2×1=24 possible sequences. This procedure can then be repeatedalternately until the film reaches a desired thickness.

[0040] An example is the sequence a c (a c a c . . . ). This is theprior art ALD process where one of the first precursors flows withoutbeing excited by the plasma to form a layer on the workpiece, and thenstops, then another of the first precursors flows without being excitedby the plasma to form another layer on the previous layer, and thenstops, and the sequence continues until the film reaches a desiredthickness. A variation of this example is the sequence b c (b c b c . .. ). In this sequence, one of the first precursors flows while beingexcited by the plasma to form a layer on the workpiece, and then stops,then another of the first precursors flows while being excited by theplasma to form another layer on the previous layer or to modify thematerial of the previous layer, and then stops, and the sequencecontinues. A specific example of this sequence isTetraDiMethylAminoTitanium (TDMAT) in a process used to produce TiNfilm. With plasma on, TDMAT is decomposed and forms a thin TiN layer(step b), then stops (step c). Then plasma-excited nitrogen and hydrogenflow to modify this thin TiN layer (step b) and then stop (step c). Thesequence continues until the film reaches a desired thickness.

[0041] Another example is the combination of the first two example a c bc (a c b c . . . ). In this sequence, one of the first precursors flowswithout being excited by the plasma to form a layer on the workpiece,and then stops, then another of the first precursors flows while beingexcited by the plasma to form another layer on the previous layer or tomodify the material of the previous layer, and then stops, and thesequence continues. A specific example of this sequence isTetraDiMethylAminoTitanium (TDMAT) in a process used to produce, TiNfilm. With plasma off, TDMAT is not quite decomposed and a thin layer ofTDMAT coats the substrate (step a), then stops (step c). Thenplasma-excited nitrogen and hydrogen flow to modify this thin TDMATlayer (step b) and then stop (step c). The sequence continues until thefilm reaches a desired thickness. A variation of this combination is thesequence b c a c (b c a c . . . ).

[0042] Another example is the sequence b c d c (b c d c . . . ). In thissequence, one of the first precursors flows while being excited by theplasma to form a layer on the workpiece, and then stops, then theambient is excited by the plasma to modify the newly deposit layer, andthen stops, and the sequence continues. A specific example of thissequence is TetraDiMethylAminoTitanium (TDMAT) in a process used toproduce TiN film. With plasma on, TDMAT is decomposed and forms a thinTiN layer (step b), then stops (step c). Then plasma-excited nitrogenand hydrogen flow to modify this thin TiN layer (step b) and then stop(step c). Then the plasma-excited ambient also modifies this thin TiNlayer (step d) and then stop (step c). The sequence continues until thefilm reaches a desired thickness. A variation of this example is thesequence a c d c (a c d c . . . ). In this sequence, one of the firstprecursors flows without being excited by the plasma to form a layer onthe workpiece, and then stops, then the ambient is excited by the plasmato modify the newly deposit layer, and then stops, and the sequencecontinues.

[0043] Another example is the sequence a b c (a b c . . . ). In thissequence, one of the first precursors flows without being excited by theplasma to form a layer on the workpiece, then this precursor flow whilebeing excited by the plasma to form another layer on the workpiece or tomodify the material of the previous layer, and then stop. A variation ofthis sequence is a b d c (a b d c . . . ). In this sequence, the ambientis excited by the plasma to modify the newly deposit layer beforestopping.

[0044] Another example is the sequence b a c (b a c . . . ). In thissequence, one of the first precursors flows while being excited by theplasma to form a layer on the workpiece, then this precursor flowwithout being excited by the plasma to form another layer on theworkpiece or to modify the material of the previous layer, and thenstop. A variation of this sequence is d b a c (d b a c . . . ). In thissequence, the ambient being excited by the plasma to clean the surfacebefore the precursor flows.

[0045] Although a few of the sequences of practicing the method of theinvention has been disclosed, it will be appreciated that there are manymore sequences and further modifications and variations thereto may bemade while keeping within the scope of the invention as defined in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0046]FIG. 1 shows the present invention plasma enhanced atomic layerdeposition system.

[0047]FIG. 2 shows another embodiment of the present invention plasmaenhanced atomic layer deposition system.

[0048]FIG. 3 shows the pulsing manifold of precursor source.

[0049]FIG. 4 shows the characteristic table of step a and step b of thepresent invention method of deposition.

[0050]FIG. 5 shows the characteristic table of step a, step b, step c,and step d of another embodiment of the present invention method ofdeposition.

[0051]FIG. 6 shows the deposited layers of step a.

[0052]FIG. 7 shows the deposited layers of step b.

[0053]FIG. 8 shows the deposited layers of step c.

[0054]FIG. 9 shows the deposited layers of step d.

[0055]FIG. 10 shows the deposited layers of sequence b a b.

[0056]FIG. 11 shows the deposited layers of sequence a c a c.

[0057]FIG. 12 shows the deposited layers of sequence b c b c.

[0058]FIG. 13 shows the deposited layers of sequence b c d c.

[0059]FIG. 14 shows the deposited layers of sequence a b c.

[0060]FIG. 15 shows the deposited layers of sequence a b d c.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT

[0061]FIG. 1 shows the present invention plasma enhanced atomic layerdeposition system. The system includes a process chamber 7 with aworkpiece 6 for deposition of layered films. Heater 17 controls thetemperature of the workpiece 6 to the process temperature. An energysource 10 generates a plasma inside the process chamber 7. The plasma ishaving two stages: 4 and 5. These stages are controlled by a plasmaadjusting system (not shown) to increase the plasma from position 4 toposition 5 and vice versa. The plasma adjusting system in FIG. 1controls the plasma power, with plasma 4 of less power than plasma 5. Byincreasing the plasma power, more gas is ionized and the plasma volumeincreases. The process chamber includes 2 first precursor inlets 12 and15 having precursor flows 1 and 11 respectively. These first precursorsand the plasma source are positioned in such a way that plasma 4 doesnot excite the precursors 1 and 11. With plasma 5, the precursors 1 and11 are excited, thus the system uses plasma pulsing to pulse the energyof the precursors 1 and 11. The system further includes a secondprecursor inlet 13 having precursor flow 2. This precursor 2 is notexcited by the plasma because of its position beneath the plasma area.The system further includes a third precursor inlet 14 having precursorflow 3. This precursor 3 is always excited by the plasma because of itsposition as always passing through the plasma area. An exhaust 9maintains an exhaust flow 8 to keep the chamber at the desired pressure.

[0062]FIG. 2 shows another embodiment of the present invention plasmaenhanced atomic layer deposition system. This system used a electrode 22controlled by a voltage source 21 to adjust the plasma area. Bygrounding the electrode 22, the plasma is terminated at this electrode22. Leaving the electrode 22 float, the plasma will ignore thiselectrode and resume its large area.

[0063]FIG. 3 shows the pulsing manifold of precursor source. Precursorinlet is 31. Chamber inlet is 32 and vacuum pump exhaust is 33. Byswitching the valves 34 and 35, the precursor flow 31 is effectivelybeing pulsed. When valve 34 open and valve 35 close, the precursor flowsinto the chamber. When valve 34 close and valve 35 open, the precursorflows to the exhaust. This pulsing manifold allow fast switching of theprecursor flow without the need for gas flow stabilization.

[0064]FIG. 4 shows the characteristic table of step a and step b of thepresent invention method of deposition. The first precursor gas 1 iscontrolled by the plasma position. When the plasma is on, the gas 1 isexcited. When the plasma is off, gas 1 is not excited. The secondprecursor gas 2 is always not excited by the plasma and the thirdprecursor gas 3 is always excited by the plasma.

[0065]FIG. 5 shows the characteristic table of step a, step b, step c,and step d of another embodiment the present invention method ofdeposition. Steps a and b are the same as in FIG. 4, applicable when gas1 is flowing. When gas 1 is not flowing, the ambient, composed ofresidue gas, is controlled by the plasma power. The ambient gas isexcited by the plasma when the plasma is on. When gas 1 is flowing andthe plasma is on, the ambient gas is small compared to gas 1, thus itseffect is negligible.

[0066]FIG. 6 shows the deposited layers of step a: not-excited gas 1flows. With certain temperatures, no film is deposited on the substrate40 (path 44). With the right temperature, a layer 43 is deposited on thesubstrate 40 (path 45).

[0067]FIG. 7 shows the deposited layers of step b: excited gas 1 flow.The excited gas 1 could react with the present layer 49 and convertslayer 49 to another layer 51 with different property (path 53). Theexcited gas 1 could deposit a layer 52 on the existing layer 49 on topof the substrate 46 (path 54).

[0068]FIG. 8 shows the deposited layers of step c: no gas 1 flow and noexcited ambient. Nothing happens, layer 56 on substrate 55 is stilllayer 56 on substrate 55 (path 57).

[0069]FIG. 9 shows the deposited layers of step d: no gas 1 flow and theambient is excited. The plasma excited ambient reacts with the layer 61on substrate 60. Layer 61 undergoes reaction to become layer 62 withdifferent property (path 63).

[0070]FIG. 10 shows the deposited layers of sequence b a b. Theworkpiece starts with layer 71 on substrate 70. After step b (path 75),a layer 72 is deposited on layer 71. The temperature is chosen such thatno reaction occurs during step a, thus nothing happens to the workpiece(path 76). After another step b, layer 72 could undergo plasma reactionto become layer 74 with different property (path 77), or could have alayer 73 depositing on layer 72 (path 78).

[0071]FIG. 11 shows the deposited layers of sequence a c a c. Theworkpiece starts with layer 81 on substrate 80. After step a, a layer 82is deposited on layer 81 (path 84). Step c cleans out the offprecursors, thus nothing happens to the workpiece (path 85). Anotherstep a deposits layer 83 on layer 82 (path 86). Step c cleans out theoff precursors, thus nothing happens to the workpiece (path 87).

[0072]FIG. 12 shows the deposited layers of sequence b c b c. Theworkpiece starts with layer 91 on substrate 90. After step b, a layer 92is deposited on layer 91 (path 94). Step c cleans out the offprecursors, thus nothing happens to the workpiece (path 95). Anotherstep b could form a reaction with layer 92 to create layer 99 havingdifferent property (path 96) or could deposit layer 93 on layer 92 (path97). Step c cleans out the off precursors, thus nothing happens to theworkpiece (path 98).

[0073]FIG. 13 shows the deposited layers of sequence b c d c. Theworkpiece starts with layer 101 on substrate 100. After step b, a layer102 is deposited on layer 101 (path 104). Step c cleans out the offprecursors, thus nothing happens to the workpiece (path 105). Step dforms a reaction with layer 102 to create layer 103 having differentproperty (path 106). Step c cleans out the off precursors, thus nothinghappens to the workpiece (path 107).

[0074]FIG. 14 shows the deposited layers of sequence a b c. Theworkpiece starts with layer 111 on substrate 110. After step a, a layer112 is deposited on layer 111 (path 114). A step b could form a reactionwith layer 112 to create layer 118 having different property (path 115)or could deposit layer 113 on layer 112 (path 116). Step c cleans outthe off precursors, thus nothing happens to the workpiece (path 117).

[0075]FIG. 15 shows the deposited layers of sequence a b d c. Theworkpiece starts with layer 121 on substrate 120. After step a, a layer122 is deposited on layer 121 (path 134). A step b could form a reactionwith layer 122 to create layer 124 having different property (path 135)or could deposits layer 123 on layer 122 (path 136). Step d does nothave an effect on layer 124 (path 137) or forms a reaction with layer123 to create layer 125 having different property (path 138). Step ccleaning out off precursors, thus nothing happens to the workpiece (path139).

[0076] Although a preferred embodiment of practicing the method of theinvention has been disclosed, it will be appreciated that furthermodifications and variations thereto may be made while keeping withinthe scope of the invention as defined in the appended claims.

What is claimed is:
 1. A method for depositing a highly controlledlayered film on a workpiece in a process chamber within a processsystem, the process system further comprising a plurality of firstprecursor sources coupled to the process chamber for providing acontinous flow of at least one precursor therein; an energy sourcecoupled to the process chamber for generating a plasma; and a plasmaadjusting system configured to control the energy source for turning onand turning off the plasma; the method comprising the steps of: a)turning on the plasma for about one second or longer to excite theprecursors from the first precursor sources to promote a plasma-enhancedreaction of the precursors at the workpiece surface, and b) turning offthe plasma for about one second or longer to prevent plasma excitationof the precursors from the first precursor sources, whereby preventing aplasma-enhanced reaction of the precursors at the workpiece surface. 2.The method of claim 1 wherein the steps a) and b) are repeated until thelayered film reaches a desired thickness.
 3. The method of claim 1wherein the energy source is selected from a group consisting ofinductive coupled plasma (ICP) source, capacitance plasma source,microwave guide plasma source, electron cyclotron resonance (ECR) plasmasource, magnetron plasma source, DC power plasma source.
 4. The methodof claim 1 wherein the process system further includes a heater sourceto heat the workpiece to a process temperature.
 5. The method of claim 1wherein the process system further includes a second precursor sourcefor providing at least one precursor to the process chamber, theprecursor from the second precursor source being provided only when theplasma is turned off.
 6. The method of claim 1 wherein the processsystem further includes a third precursor source for providing at leastone precursor to the process chamber, the precursor from the thirdprecursor source being provided in such a way so that the thirdprecursor is not excited by the plasma when the plasma is turned on. 7.The method of claim 1 wherein the process system further includes afourth precursor source for providing at least one precursor to theprocess chamber, the precursor from the fourth precursor source beingprovided only when the plasma is turned on.
 8. The method of claim 1wherein the plasma-on power level is in the range of 15 to 6000 watts.9. The method of claim 1 further comprising a step c) after the step a):c) evacuate the precursors from the first precursor sources; whereby thestep c) can be concurrent with step b), before step b) or after step b).10. A method for depositing a highly controlled layered film on aworkpiece in a process chamber within a process system, the processsystem further comprising a plurality of first precursor sources coupledto the process chamber for providing a pulsed flow of at least oneprecursor therein; an energy source coupled to the process chamber forgenerating a plasma; and a plasma adjusting system configured to controlthe energy source for turning on and turning off the plasma; the methodcomprising the steps of: a) turning on the plasma for about one secondor longer to excite the precursors from the first precursor sources topromote a plasma-enhanced reaction of the precursors at the workpiecesurface, and b) turning off the plasma for about one second or longer toprevent plasma excitation of the precursors from the first precursorsources, whereby preventing a plasma-enhanced reaction of the precursorsat the workpiece surface, whereby the pulsed flow of the precursors fromthe first precursor sources is substantially synchronized with theplasma adjusting system so that there is no precursor flow when theplasma is off and there is precursor flow when the plasma is on.
 11. Themethod of claim 10 wherein the steps a) and b) are repeated until thelayered film reaches a desired thickness.
 12. The method of claim 10wherein the energy source is selected from a group consisting ofinductive coupled plasma (ICP) source, capacitance plasma source,microwave guide plasma source, electron cyclotron resonance (ECR) plasmasource, magnetron plasma source, DC power plasma source.
 13. The methodof claim 10 wherein the process system further includes a heater sourceto heat the workpiece to a process temperature.
 14. The method of claim10 wherein the process system further includes a second precursor sourcefor providing a continuous flow of at least one precursor to the processchamber.
 15. The method of claim 10 wherein the process system furtherincludes a third precursor source for providing at least one precursorto the process chamber, the precursor from the third precursor sourcebeing provided only when the plasma is turned off.
 16. The method ofclaim 10 wherein the process system further includes a fourth precursorsource for providing at least one precursor to the process chamber, theprecursor from the fourth precursor source being provided in such a wayso that the fourth precursor is not excited by the plasma when theplasma is turned on.
 17. The method of claim 10 wherein the plasma-onpower level is in the range of 15 to 6000 watts.
 18. The method of claim10 further comprising a step c) after the step a): c) evacuate theprecursors from the first precursor sources; whereby the step c) can beconcurrent with step b), before step b) or after step b).
 19. The methodof claim 18 wherein the evacuation of precursor is performed by pumpingthe process chamber.
 20. The method of claim 18 wherein the evacuationof precursor is performed by flowing another precursor into the processchamber.